Post on 12-Jun-2015
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GENETICS AND INHERITANCE
Genetics- is the study of
heredity
Heredity-is the relation
between successive genes.
GENETICS
THE FATHER OF GENETICS
The father of Genetics is
Gregory Mendel
He discovered the basic
principles of heredity by
breeding the garden peas in a
carefully planned experiment.
FATHER OF GENETICS
Cross pollination-Is the fertilization between different plants.
True breeding-The organisms with only one variety type (white flowers can only produce white flowers).
Hybridization-Mating two true breeding, contrasting varieties.
FATHER OF GENETICS
Law of segregation states that two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
LAW OF SEGREGATION
TWO TYPES OF GENETIC CROSSES
Monohybrid cross-A cross between 2 organisms where we only look an one pair of contrasting traits.
Dihybrid cross-A cross between 2 organisms where we look at two pairs of contrasting traits at the same time.
MONOHYBRID CROSSES
DIHYBRID CROSSES
Law of independent assortment states that each pair of alleles segregates independently of each other pair of alleles during gamete formation.
LAW OF INDEPENDENT ASSORTMENT
Two varieties of chromosomes: The larger X and the smaller Y
SRY gene on the on the Y chromosome codes for testes development.
Females are XX and Males are XY
DERTEMINING SEX OF THE BABBY
THE DIAGRAM TO DERTEMINE THE SEX OF THE BABY
sex chromosomes have genes for many characters unrelated to sex
gene located on either sex chromosome is called a sex-linked gene
For a recessive sex-linked trait to be expressed• A female needs two copies of the allele• A male needs only one copy of the allele
INHERITANCE OF SEX LINKED GENES
DISORDERS CAUSED BY RECESSIVE ALLELES ON THE X CHROMOSOME IN HUMANS:
Colour blindness
Duchene muscular dystrophy
Haemophilia
D I S O R D E R S C A U S E D BY R E C E S S I V E A L L E L E S O N T H E X C H R O M O S O M E I N H U M A N S :